ADD Extracellular matrix

Question 1

What is the extracellular matrix and what does it regulate?

Answer 1

-extracellular meshwork of proteins + hydrated macromolecules
-regulates: migration, tissue integrity + cell shape, proliferation, differentiation

Question 2

Describe the appearance of the extracellular matrix

Answer 2

-collagen + elastic fibres to make skin robust
-sugar chains to hold water
-basal lamina

Question 3

What are the different types of extracellular matrix?

Answer 3

-fibrous proteins - structural proteins (collagens + elastin)
-adhesion proteins (fibronectin + laminin)
-hydrated macromolecules

Question 4

Describe the structure of collagens

Answer 4

-repetitive structure - have glycine-proline-hydroxyproline triplet repeats
-triple helix - 3 different alpha peptide chains align

Question 5

What produces collagens?

Answer 5

Fibroblasts + epithelial cells

Question 6

What is an example of a disease caused by a collagen defect?

Answer 6

Ehlers-Danlos syndrome - leads to degradation of skin integrity

Question 7

What is fibrillin?

Answer 7

The scaffold over which elastin will be laid down

Question 8

What is an example of a disease caused by a fibrillin defect?

Answer 8

Marfan syndrome - fibrillin deformation means tension not applied to bones, resulting in longer limb length

Question 9

What are GAG’s Glycosaminoglycans?

Answer 9

-disaccharide chains typically 70-200 units long
-highly charged so hold water effectively
-serine is substituted for a hydroxyl group

Question 10

What are the different adhesion glycoproteins?

Answer 10

-laminin
-fibronectin
-integrins

Question 11

What is laminin?

Answer 11

-makes up the basal lamina
-epithelial cells sit on basal lamina + form epithelium
-has many functional domains as it needs to interact more with other molecules

Question 12

What is the structure of fibronectin?

Answer 12

-has many domains
-forms disulfide bonds to link to itself
-has self-association motifs
-has collagen binding domains
-has cell binding domains, so will interact with integrins on the surface of cells

Question 13

What are integrins, what is their structure and how do they work?

Answer 13

-transmembrane receptors that allow cells to stick to another molecule
-made up of an alpha + beta subunit
-bind matrix through divalent cations
-removal of cations cause cells to detach